The present invention (per Formula I) relates to novel tetrahydro-1H-pyrido[3,4-b]indoles having a 4-pyridinylalkyl, 2-pyrazinylalkyl, or 2-, 3-, or 4-quinolinylalkyl substituent attached to the pyrido nitrogen. The compounds may be substituted on the benzene ring of the nucleus and at the indole nitrogen. The 4-pyridinyl, 2-pyrazinyl, and 2-, 3-, or 4-quinolinyl rings may also be optionally substituted (R.sub.3). The compounds of the invention are useful as antihypertensive agents. The invention also includes pharmaceutical compositions having said compounds as the active ingredient and a method of treating hypertension by administering an antihypertensive effective amount of a compound of the invention to a mammal in need of antihypertensive treatment.
The present invention (per Formula XX) further relates to novel tetrahydro-1H-pyrido[3,4-b]-indoles having a 2- or 3-pyridinylalkyl substituent attached to the pyrido nitrogen. These compounds may be optionally substituted on the benzene ring of the nucleus but have only hydrogen on the indole nitrogen. The compounds of the aspect of the invention are useful as antipsyhchotic agents. This aspect of the invention also includes pharmaceutical compositions having said compounds as the active ingredient and a method of treating psychosis by parenterally administering an anti-psychotically effective amount of a compound of this aspect of the invention to human or animal in need of psychotropic therapy.
The 2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole nucleus of the compounds of the invention is also referred to as a tetrahydro-.beta.-carboline nucleus. The closest prior art disclosure of such tetrahydro-.beta.-carboline derivatives to Applicants' compounds of Formula I of the invention are described in the Japanese Kokai No. 22853, published on Oct. 14, 1964, to Fujisawa Pharmaceutical Co. Ltd., which is found in Derwent Abstracts No. 14306F. The .beta.-carbolines of this Fujisawa Japanese patent disclosure have an aminopropyl or N-heteropropyl substituent on the pyrido nitrogen of the .beta.-carboline nucleus and are described as being sedatives and anti-hypertensives. The Fujisawa compounds, therefore, differ from Applicants' compounds in having the alkylene bridge attached to the nitrogen of an amino or a non-aromatic heterocyclic group. Applicants' compounds have a monocyclic or bicyclic aromatic nitrogen heterocyclic group attached at the distal end of the alkylene bridge, with said attachement being to a carbon atom instead of the nitrogen heteroatom.